This invention is founded on a micro-fabricated structure of 3D electrode array. It proposes an integrally packaged, solid-state lithium rechargeable microbattery with a 3-dimensional interpenetrating-electrode internal architecture. The microbatteries are fabricated either through sputtering or colloidal scale self-organization and have the capability for outer package aspect ratios of less than 5:1 for maximum to minimum dimensions and active materials packing fraction of >75% in a 1mm3 volume, which allows them to be used in i-UHDs. . The proposed approach will use currently available and proven cathode and anode materials, but will allow drop-in of higher energy or higher rate active materials as they are developed in the future.